Screen stays dark at start-upGeneral

1) For a few months, my wifi 10.1 has often been booting up to a dark screen. once it has started up I can get the screen to light up by putting it to sleep and then waking it with two taps to the power button.

2) Last week, I got MOST of the way through rooting when I must have done something wrong, since I don't appear to have root. It was long enough ago that I do not recall what step I was last at.

So, you'd think I could just restart rooting at the beginning, but because of the dark screen (which has suddenly started happening 100% of the time), I can't get into the download or recovery modes; the screen stays dark while I hold PWR and VOL-, intermittently flashing the Samsung logo, but never showing the options I want. When I give up after 2-3 minutes and let go of the buttons, it boots darkly as usual.

Any suggestions for the dark boot or a different way to get to recovery/download on my Tab 10.1? I'm all ears.